1. Field of the Invention
This invention relates generally to optical wireless communication links, and more particularly, to a method of reducing the control packet transmission rate for an optical wireless link.
2. Description of the Prior Art
An optical wireless link system consists of two stations (OWLs): Each of which contains an optical transmitter and an optical receiver. The transmitter is able to change the direction of its transmitted beam by known amounts of angular displacement. The receiver sees this motion and sends position correction information back to the transmitter. This feedback is used by a servo control loop to position the transmitted beam on the receiver of the remote station.
After two optical wireless units are aligned, some method is required to detect when the optical link is broken. This method most preferably has minimal impact on the system performance. Sending and processing position control packets in an optical wireless link requires significant computational overhead; and depending on the transfer rate, may significantly impact available bandwidth in the link.
In view of the foregoing, it would be both desirable and advantageous in the optical wireless communication art to provide a technique that does not rely on signal strength for detecting the presence of a broken optical wireless link. Additionally it is advantageous for the method to work in a variety of lighting conditions (outdoors/indoors, lights on/off, night/day).